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Amitochondriate protists: Symbiotic trichomonads of dry-wood-eating termites
Comparative cytological and molecular phylogenetic data suggest that amitochondriate trichomonads (Archaeprotista: Parabasalia) are an early branching lineage of eukaryotes. Prominent in their cells is the karyomastigont, a cytoskeletal organellar system that includes a nucleus, 4–5 kinetosomes, an axostyle, a parabasal body (Golgi complex), and associated fibers. The karyomastigont is an ancestral character of eukaryotes. Genera of the trichomonad family Calonymphidae (Calonympha, Coronympha, Metacoronympha, Stephanonympha and Snyderella) are polymastigont: multinucleate cells with many karyo- or akaryomastigonts (karyomastigonts that lack nuclei). Termite hindgut trichomonads were examined for their susceptibility to antibiotics, pattern of cell division, and to test the hypothesis that DNA is associated with centriole-kinetosomes. ^ Several types of bacterial symbionts are harbored on the surface membranes, in the cytoplasm and nuclei of these anaerobic protists rendering them susceptible to antibacterial antibiotics. Caduceia sp., a devescovinid trichomonad with four types of bacterial symbionts, was removed within 14 days from the Cryptotermes cavifrons (Florida) gut when penicillin and streptomycin were fed to the termite. Snyderella tabogae was far less susceptible to the antibiotic treatment, which also enhanced formation of calcium-rich crystals in the intestine. ^ Metacoronympha divides asymmetrically. M. senta from Incisitermes nr. incisus (Trinidad) also showed a bimodal distribution of cell size. Approximately one third of the population averaged 100 μm in length with as many as 1000 karyomastigonts, unlike the previously described 50 μm mean length with up to 350 karyomastigonts. ^ The cytoskeleton of Snyderella tabogae, the only calonymphid whose complete set of nuclei are not attached to centriole-kinetosomes, consists solely of 500 or more akaryomastigonts (>2000 undulipodia and their kinetosomes). In Snyderella tabogae, groups of 20–50 akaryomastigonts simultaneously beat and form locally organized regions of the cortex. These polymastigont cells are ideal to seek centriole-kinetosome-associated DNA. Fluorescent cytological (DAPI, SYTOX, acridine orange, ethidium bromide, propidium iodide) as well as Feulgen stains were negative: no DNA was present in the centriole-kinetosomes of S. tabogae. However, DAPI accumulates in the parabasal bodies (Golgi complex). ^
Biology, Entomology|Biology, Cell|Biology, Microbiology
Michael Francis Dolan,
"Amitochondriate protists: Symbiotic trichomonads of dry-wood-eating termites"
(January 1, 1999).
Doctoral Dissertations Available from Proquest.